Studying Procedural Approach to VFX in Houdini

Introduction

My name is Glenn Dawick, I’m a freelance 3D generalist interested in all forms of 3D mostly surrounding realism. I’m comfortable working on most processes in the 3D pipeline, my favourites being modelling, lighting, materials, camera tracking, and more recently rigid and soft body dynamics, alongside natural phenomena like particles, water, fire, and smoke effects.

I first discovered the 3D industry as a potential career path while studying graphic design, straight out of college. I had always been interested in art and design at different levels ever since I was kid, so the idea of bringing still images into the moving world of 3D animation was an appealing thought that made the transition from paper to screen an exciting endeavour.

Throughout my 3D career, during what feels like hundreds of projects mostly in the TV and online advertising industry with a few smaller roles in film, I’ve worked on anything to everything from toilet rolls to food, all the way up to vehicles, landscapes, creatures, and talking animals.

I’m currently practising newly learnt techniques and building up new showreel pieces after recently finishing the Diploma Of Advanced Houdini FX at CG Spectrum, alongside freelancing at a mid-sized post-production facility in my home-town Auckland, New Zealand.

About the Education

I had been keeping an eye on Houdini for quite some time, being impressed with its capabilities, and how often it was being used in many incredible movie shots. I knew learning Houdini would be the next step in advancing myself in the 3D industry.

Mid last year, I was unfortunately made redundant due to many months of slow work at the studio I was employed at. This actually turned out for the better, as it gave me the break I needed to put full effort into advancing my 3D skills with some additional training.

I did a lot of online research via forums, reviews, student showcases as well as checking out the pros and cons of studying full-time vs selectively picking shorter training videos that focused on singular effects. After much research, I decided CG Spectrum would be the one with the most benefits.

I was impressed by the Advanced Houdini FX student showcase, but the biggest draw was the idea of being trained by current industry professionals. Being able to talk directly with the pros about questions and issues you’d face while learning, alongside the weekly live video sessions, made the choice of going with CG Spectrum an easy one.

My goals were to finish the course with the confidence to tackle tasks I was never capable of working through before. I have worked full-time with a few different post-production houses and noticed Houdini type effects being farmed out to external freelancers. Becoming knowledgeable in these areas was the main focus, particularly around oceans, fire, smoke, rigid body dynamics, and particle effects.

With the proper knowledge, I’ve learned these types of effects aren’t as scary to take on as they first seem. The way, CG Spectrum lays out its learning path making sure you’re correctly learning the fundamentals required to successfully move on to the more advanced steps in the process. It can seem daunting at first, but breaking the steps into smaller chunks and first understanding those makes moving forward much easier.

Anyone with a passion for 3D and a want to advance themselves in these areas should have no trouble achieving this goal.

About Procedural Approach

Before working with Houdini, the word procedural basically only meant texturing to me. The rest of the work was always a step somewhere in the process that had to be done at a specific point in time, and it was always difficult going back to fix or replace those parts if they weren’t built correctly.

I wouldn’t say you need any specific knowledge on procedural node-based systems before starting to use one, although it can be a little strange at first coming from say, a Maya background, where each object has a history in a certain order.

At first, I thought there were too many nodes to deal with in order to achieve a specific result, but you can very quickly see the benefit and power of being able to swap out, alter or change any step in your process and have everything ripple update all the way through your node chain to your final output.

Making use of collapsible network boxes, subnetworks, node colors, and notes means you’ll never get lost in your own networks, which can get very complex. This also makes it possible for another team member to pick up your scene and continue where you left off.

Practicing VFX

In terms of working with the many effects available in Houdini, it’s not so much an inspiration, but a desire to learn how each effect is built and what their capabilities are.

I’m not really building specific pieces to try and show off a certain effect. It’s more wanting to find out and more about the processes I’ve learnt the basics of. I’m trying to move the skills I’ve learnt into bigger, more impressive showreel pieces. I’m constantly hitting walls and getting stuck, which forces you to learn and correctly work your way through problems. I think this is an important part for your own self-learning and discovery of what the tools are capable of.

Inspiration, on the other hand, can come from anything and everything! Something as simple as a colour palette can spark the imagination. Besides your own quirky brain, searching around online for others’ work is the best way to get started. There’s an infinite supply of incredible artists out there who are all inspired by each other. Find artists you like and build on their ideas.

This sounds cheesy, but see how far you can push your own effects and bring your original inspiration to new heights. Keep adding effects or intricacies to your simulations to build something bigger and better!

Hair and Groom Simulation

The fur, hair, and grooming tools available in Houdini are incredible and surprisingly easy to work with once you understand the order of operations. The shelf tools make it easy to achieve a quick basic setup that you can customize to suit whatever you’re aiming for. Through trial and error, I’ve learned the number of constraint iterations and substeps play a huge part in getting the hair to simulate properly, without penetrating the collision geometry, stretching, or flickering.

It’s always a good idea to start small and work your way up to the final effect. It can be much easier and faster to work on a smaller isolated selection of your model. Being able to simulate that smaller section quickly to see how each of your edits is affecting the simulation makes it far easier to make informed changes without forgetting which parameters you’ve altered to achieve the look you’re going for.

Working with Particle System

Particles are an incredibly versatile 3D element that you’d typically use to simulate the intricate movements of anything like dust, sparks, snow or dirt, microscopic specs floating in air, or water, they can be used as the base for a liquid simulation, to create stars and galaxies, or to instance other objects onto when creating something like debris from an explosion, falling leaves or bouncing balls. The list is endless.

Coming from a Maya background, particles are a little different in Houdini. Particles are just points (or vertices in Maya) that can be connected or independent from a mesh. This seems weird coming from Maya, where a vertice cannot exist without its surrounding edges.

Particles can be born multiple times from a single point, or all the points can first be created before the simulation starts. So you could either start with a pool full of points to represent water, or you could be emitting points from a hose to fill that pool.

In the past, I’ve used particles to create magic-like effects similar to fairy dust or glowing magic spells. This effect is usually created by emitting thousands of individual points from a single source, giving those points properties like weight, color or transparency and then applying an overall force to those points, creating advection to push and pull them around in the air. Something like a detailed snowflake model could then be instanced onto each particle at render time to create nice reflections by catching the light at different angles as the snowflake drifts, rotates, and moves around through the air.

Creating Bubbles 

I created this to try and re-create an image I found of oil floating in the water. The intricate patterns of thousands of microscopic bubbles of varied sizes clinging to each other looked mesmerizing. I was trying to replicate this image and see the bubbles moving in action.

This effect is using particles setup as Houdini Grains. Normally, particles don’t speak to each other in terms of collisions, but given the grain attribute, they use position-based dynamics to collide with each other. The grains can be of different sizes and be given the same properties as regular particles.

I applied a few different forces to push and pull them around and looking top-down onto the points, used a rule to tell them not to move in the Y-direction. With their position locked in Y and the swirling forces pushing them around, they crash into each other, but can’t move above or below each other. I think I managed to replicate the reference image fairly well and the resulting movement makes for a mesmerizing view.

Biggest Challenges 

Being a Maya user for more than 10 years, I guess the biggest challenge for me was breaking my perception of how I thought a typical 3D workflow should run. It seems crazy to think back now at all the things you put up with, given that’s how you’ve always done them. You seem to be hacking things to get fixed, instead of accurately tackling the problems with the correct tools. The node-based workflow opens new horizons on what changes can be made to your scene file on the last day of your project to an effect that you started building on day one.

I’ve only just touched the surface of what Houdini is capable of and I’m learning new things every day. I’m excited to think of the many future projects Houdini is going to help me out on.

With everything I’ve learned, I hope to open my freelance work up not only to more local post-production houses, but also other talented artists and studios worldwide.

Ways to Learn Houdini

Well, I can only say good things about CG Spectrum, given I had never touched Houdini before this. In the short space of 10 months, I’m extremely happy with what I’ve learned and what I’m now capable of achieving in my work following this.

There are thousands of individual tutorials covering singular effects available online, many of them free or cheap. I looked into these before studying but felt some of them glazed over crucial steps in the process, not going into enough explanation or depth on what each node is capable of, or what else that particular node can be used for.

Depending on your level of understanding in Houdini, this might be ok for you, but for new users wanting to learn in an efficient specifically guided layout, I would suggest a longer course like CG Spectrum’s Advanced Houdini FX Diploma.

Working your way from the basics all the way up to advanced effects makes sure you know what each of the many tools available to you is capable of and how they can be used in connection with each other to create varying results.

Glenn Dawick, VFX artist

Interview conducted by Ellie Harisova